This application, A Randomized Trial of the STAR Program for Children with Autism Spectrum Disorders, capitalizes on the impending implementation of STAR (Strategies for Teaching Based on Autism Research) in the School District of Philadelphia and seeks support to conduct a randomized controlled field trial of this classroom-based program. The primary aims are to examine the effects of STAR versus the comparison condition on academic progress and impairments associated with ASD. We will assess changes, over the course of an academic year, in: 1. School readiness, with a focus on pre-academic skills; 2. Communication, including use of expressive and receptive language; 3. Socialization and social skills;and 4. Adaptive and challenging behaviors. The secondary aims are to examine the potentially moderating role between STAR and these outcomes of: 1. Children's symptoms and chronological and developmental age at baseline; 2. Teacher effects, specifically fidelity of program implementation and training and experience; 3. Other interventions received prior to and concurrent with the study period;and 4. Family characteristics. The Philadelphia School District plans to use STAR for the approximately 330 children in 42 kindergarten- through-2nd grade autism support classrooms starting in September 2008. If this proposal is funded, the district will randomize teachers and aides in half of these classrooms to STAR training and delay training the other half until 2009. Teachers in the latter group will receive training of equal intensity in Structured Teaching, the district's current standard of care. Measures will be taken at the beginning, middle and end of the academic year. Child measures will address academic progress, communication, socialization and behavior, clinical presentation and use of other interventions. Teacher measures will include knowledge, experience, and job-related stress. We will assess program fidelity through independent observations. Findings from the proposed study would provide timely and critical evidence regarding the implementation and effectiveness of one promising practice, with direct relevance to translation of findings into practice and policy.